Seroprevalence of Trypanosoma cruzi (TC) and risk factors in Colima, Mexico.

INTRODUCTION: The present study was conducted to estimate the incidence of seropositivity to anti-Trypanosoma cruzi antibodies and analyze potential risk factors in Colima, on the western coast of Mexico. METHODOLOGY: Longitudinal studies of 209 subjects with negative serology in 1999 for anti-Trypanosoma cruzi antibodies by hemagglutination inhibition test were tested again in 2005. At the same time, 716 children under six years of age were surveyed serologically (total n = 925); the history of Trypanosoma cruzi infection was determined by the same hemagglutination inhibition test. The variables analyzed were age, sex, living in triatomine-infested places, type of community, quality of housing, presence of pets, and number of inhabitants per house. RESULTS: Trypanosoma cruzi seropositivity in the period of six years was 22/925 cases, with a point prevalence of 2.73% and an adjusted rate of 7.3/1,000 person-years. The variable living in triatomine-infested areas showed association with seropositivity anti-Trypanosoma cruzi antibodies (RR: 5.5; 95% CI: 1.28-23.5). The remaining variables showed no significant association. CONCLUSIONS: This study confirms the active transmission of Chagas disease in Mexico´s western-central region, which merits greater epidemiological surveillance and vector control, particularly in localities infested with triatomines.

Effect of an ecosystem-centered community participation programme on the incidence of dengue. A field randomized, controlled trial.

OBJECTIVES: The purpose of this study is to analyse the effect of a community participation programme based on the ecosystem model on the incidence of dengue in urban communities. METHODS: A randomized controlled field trial was conducted in the state of Colima, Mexico. The intervention consisted of a community participation programme focused on the ecosystem; simultaneously, the control groups were communities that only received the usual official prevention programs. The incidence of dengue was estimated in people of both groups due to the appearance of de novo IgM antibodies during the follow-up period. RESULTS: The incidence of dengue in the intervened group was 2.58%/month (n = 818) and in control group 2.26%/month (n = 994), with a risk ratio of 1.14 (95% CI 0.89-1.45) and a PAF of 0.06 (95% CI - 0.056 to 0.16). The A. aegypti larval density (Breteau Index) was reduced in the treated group. CONCLUSIONS: The implementation of a community participation programme in the cities of Colima, Mexico, showed a slightly counterproductive effect on the incidence of dengue. This happened even with a reduction in the A. aegypti index.

Cost-Effectiveness of the Strategies to Reduce the Incidence of Dengue in Colima, México.

Dengue fever is considered to be one of the most important arboviral diseases globally. Unsuccessful vector-control strategies might be due to the lack of sustainable community participation. The state of Colima, located in the Western region of Mexico, is a dengue-endemic area despite vector-control activities implemented, which may be due to an insufficient health economic analysis of these interventions. A randomized controlled community trial took place in five urban municipalities where 24 clusters were included. The study groups (n = 4) included an intervention to improve the community participation in vector control (A), ultra-low volume (ULV) spraying (B), both interventions (AB), and a control group. The main outcomes investigated were dengue cumulative incidence, disability-adjusted life years (DALYs), and the direct costs per intervention. The cumulative incidence of dengue was 17.4%, A; 14.3%, B; 14.4%, AB; and 30.2% in the control group. The highest efficiency and effectiveness were observed in group B (0.526 and 6.97, respectively) and intervention A was more likely to be cost-effective ($3952.84 per DALY avoided) followed by intervention B ($4472.09 per DALY avoided). Our findings suggest that efforts to improve community participation in vector control and ULV-spraying alone are cost-effective and may be useful to reduce the vector density and dengue incidence.

Tick paralysis caused by Amblyomma maculatum on the Mexican Pacific Coast.

Tick paralysis is a rare entity in which it is necessary to identify the cause and remove the arthropod to have a rapid remission of symptoms. In the absence of an early diagnosis, the outcome can be fatal, as toxins are released from the tick's saliva as it feeds. To the best of the authors' knowledge, this is the first clinical report of the disease in Mexico and Latin America. A 22-year-old man from a rural area, who was in contact with cattle, developed ascending flaccid paralysis secondary to Amblyomma maculatum tick toxin. He presented flaccid paraplegia and arreflexia that progressed until causing dyspnea. The clinical symptoms subsided 48 h after the ticks spontaneously detached. The ticks were discovered by nursing personnel while the patient was being transferred to a regional hospital with the diagnosis of Guillain-Barré syndrome. The patient was asymptomatic on discharge from hospital and showed no further motor deterioration at a 1-month follow-up.